1. Price reflected is the weighted-average sale price for shares sold. The range of sale prices for the transactions reported was $10.40 to $11.1032 per share. The Reporting Persons undertake to provide, upon request by the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price.

2. Shares directly held by MDV VII, L.P. ("MDV"). Jonathan Feiber, a director of the Issuer, and Nancy J. Schoendorf are managing members of Seventh MDV Partners, L.L.C., the general partner of MDV. Each of Jonathan Feiber, Nancy J. Schoendorf, and Seventh MDV Partners, L.L.C. may be deemed to share voting and dispositive power over the shares held by MDV. Mr. Feiber, Ms. Schoendorf, and Seventh MDV Partners, L.L.C. disclaim beneficial ownership of the shares held by MDV except to the extent of any pecuniary interest therein. Mr. Feiber is filing his own Form 4 separately.

Remarks:

MDV VII, L.P.

12/14/2012

Nancy Schoendorf

12/14/2012

Seventh MDV Partners, L.L.C.

12/14/2012

** Signature of Reporting Person

Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person,
see
Instruction
4
(b)(v).